1. Field of the Invention
The present invention relates to novel keratin-treating compositions containing polymer-surfactant compositions and methods for using such compositions in personal care applications. The compositions are useful in treating keratin-containing substrates. Keratin substrates include, but are not limited to, animal and human skin, hair and nails. More specifically, the present invention relates to cosmetically acceptable compositions containing the compositions and methods for treating keratin.
2. Brief Description of Prior Art
There has been a long-standing desire to discover new ingredients and formulations that will improve the topical and bulk condition of keratin-based substrates such as hair, skin and nails. For example, such ingredients must have adequate adherent properties, so that they are not only adsorbed initially, but are also retained on exposure to water. This property is referred to as “substantivity,” i.e., the ability of a material to be adsorbed onto keratin and to resist removal by water rinse-off.
Hair is composed of keratin, a sulfur-containing fibrous protein. The isoelectric point of keratin, and more specifically of hair, is generally in the pH range of 3.2-4.0. Therefore, at the pH of a typical shampoo, hair carries a net negative charge. Consequently, cationic polymers have long been used as conditioners in shampoo formulations or as a separate treatment in order to improve the combability of both dry and wet hair. The substantivity of the cationic polymers for negatively charged hair coupled with film formation facilitates detangling during wet hair combing and a reduction in static flyaway during the combing of dry hair. Cationic polymers generally also impart softness and suppleness to hair.
When cationic polymers are added to shampoos (or to skin care products such as cleaning compositions) containing anionic surfactants, the formation of highly surface active association complexes generally takes place, which imparts improved foam stability to the shampoo. Maximum surface activity and foam stability, or lather, are achieved at near stoichiometric ratios of anionic surfactant to cationic polymer, where the complex is at least water soluble. Generally, cationic conditioners exhibit some incompatibility at these ratios. Compatibility gives a clear formulation, which is more desirable commercially. Incompatibility leads to a haze or precipitation, which may be aesthetically less desirable in some formulations.
Hair fixative properties, such as curl retention, are believed to be directly related to film-forming properties of cationic polymers, as well as to molecular weight, with performance generally increasing with increasing molecular weight. However, the fixative properties conferred by cationic polymers generally tend to have a reciprocal relationship to other conditioning properties, i.e., good curl retention usually means that properties such as wet combability will suffer and vice versa.
Keratin conditioning additives generally are of three primary types: cationic polymers, proteins or protein derivatives, and fatty quaternary ammonium compounds. Commonly used cationic polymers include: quaternary nitrogen-containing hydroxyethyl cellulose compounds, copolymers of vinylpyrrolidone and dimethylamino-ethylmethacrylate and mino functional polydimethyl-siloxane. Hydrolyzed animal protein has been frequently used as a keratin conditioner. Also used are natural products such as collagen and casein. Suitable quaternary ammonium compounds include such products as stearyl dimethyl ammonium chloride.
Generally, two broad areas of skin care products have been recognized as skin conditioners: emollients and humectants. Emollients generally provide improved moisture retention in the skin and plasticization or softening of the skin. Common commercial emollients include mineral oil, petrolatum, aliphatic alcohols such as stearyl alcohol, lanolin and its derivatives, glycol stearate, and fatty acids such as triethanolamine oleate. Humectants generally attract moisture, retard evaporation of water from the skin or hair surface and plasticize/soften skin. Common commercial humectants include glycerin, propylene glycol, sorbitols and polyethylene glycols.
A desirable skin conditioner should impart at least some of the attributes of an emollient or a humectant, as well as provide improved lubricity and feel to the skin after treatment and/or reduce the skin irritation caused by other components in the conditioner such as, for example, soaps, detergents, foam boosters, surfactants and perfumes. It is known by those skilled in the art that cationic polymers may be employed as skin and nail conditioners.
Sometimes, it is also desirable that the ingredients of skin and nail care products have adequate adherent properties, so that they are not only adsorbed initially, but are also retained upon exposure to water. In hair care applications, this property is referred to as “substantivity,” i.e., the ability of a material contacted with keratin of skin or nails to resist removal by water rinse-off. Generally, in the pH that is typical of use conditions, the skin and nails carry a net negative charge. Consequently, cationic polymers have long since been used as conditioners in nail and skin care formulations. The substantivity of the cationic polymers for negatively charged skin and nails leads to film formation that facilitates lubricity, moisturizing and feel.
The skin and nail conditioning properties of lubricity, moisturizing and feel are related to the film-forming properties of the cationic polymers, as well as to molecular weight, with performance increasing with increasing molecular weight, generally.
Conditioning additives including copolymers of dimethyldiallylammonium chloride and other monomers are well known; see, e.g., EP 0308189 (with acrylamide) and EP 0308190 and U.S. Pat. No. 4,803,071 (with hydroxyethyl cellulose). Amphoteric betaines have also been employed in cosmetic compositions; see GB 2,113,245 which discloses use of betainized dialkylaminoalkyl(meth)acrylate together with a cationic polymer.
The use of polymers of dimethyldiallylammonium chloride (DMDAAC) in the treatment of keratin is also known and disclosed in, for example, U.S. Pat. Nos. 4,175,572 and 3,986,825.
U.S. Pat. No. 4,923,694 to Shih et al. discloses copolymers of vinyl pyrrolidone and (meth)acrylic cationic monomers that are useful for treating hair. These polymers are able to provide good hair styling properties at low concentrations of cationic monomer, but provide limited substantivity due to their low cationic charge density. When the cationic charge density is increased, the polymers disclosed by Shih et al. become difficult to formulate with because of their decreasing compatibility with anionic surfactants.
As disclosed in U.S. Pat. No. 4,940,576 to Walsh, an excess of anionic surfactant is required when formulating with cationic polymers. The amount of the surfactant is in the range of 0.9 to 2.0 moles times the amount of the surfactant necessary to result in complete neutralization of the charges on the polymer.
There remains a need for a polymeric conditioning additive for keratin-based substrates that is easy to formulate with (easy to make clear surfactant-based formulations), provides excellent hair styling properties as well as excellent conditioning properties to hair, skin and nails.